linux-rng/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c, branch master

drm/amd/display: Scale custom brightness curve from full range

2026-08-19T14:03:37Z

Custom brightness curves use an 8-bit input signal. After exporting the full PWM range to userspace, the curve normalizer still divides requests by the physical PWM span. On panels with a nonzero minimum PWM level, this can produce a curve input greater than 255 and send an invalid backlight level to DC. Scale the userspace [0..max] range to the curve's [0..255] range instead. This retains the full advertised range and keeps the reverse readback conversion unchanged. Fixes: 8dbd72cb7900 ("drm/amd/display: Export full brightness range to userspace") Cc: stable@vger.kernel.org Signed-off-by: Akhmed Zhitaev Reviewed-by: Mario Limonciello (AMD) (Move to amdgpu_dm_backlight.c) Link: https://patch.msgid.link/20260813170959.22073-1-zhitaevakh@gmail.com Signed-off-by: Mario Limonciello Signed-off-by: Alex Deucher

drm/amd/display: Replace amdgpu_dm_kunit_helpers.h with dm_helpers.h

2026-07-28T22:32:36Z

Drop the amdgpu_dm_kunit_helpers.h include across the amdgpu_dm source files and use dm_helpers.h instead Assisted-by: Copilot:Claude-Opus-4.8 Reviewed-by: Alex Hung Signed-off-by: Bhawanpreet Lakha Signed-off-by: Wayne Lin Tested-by: Dan Wheeler Signed-off-by: Alex Deucher

drm/amd/display: Force PWM backlight on Lenovo Legion 5 15ARH05

2026-07-15T13:15:43Z

The Lenovo Legion 5 15ARH05 (Renoir) ships a BOE 0x08DF eDP panel that advertises AUX/DPCD backlight control, so amdgpu's automatic detection (amdgpu_backlight == -1) selects AUX. On this panel the AUX backlight path has no effect: brightness writes are accepted but the panel level never changes, the display is stuck at a fixed brightness and max_brightness is reported as a bogus 511000. As a result neither the desktop brightness slider nor the brightness hotkeys do anything. Forcing PWM backlight (amdgpu.backlight=0) restores working control: max_brightness becomes 65535 and the level tracks writes. This has long been applied by users as a manual kernel-parameter workaround. Extend the generic panel backlight quirk with a force_pwm flag, add an entry for the Legion 5 15ARH05 / BOE 0x08DF panel, and have amdgpu disable AUX backlight (use PWM) when the quirk matches and the user lets the driver auto-select the backlight type. Signed-off-by: Alessandro Rinaldi Tested-by: Alessandro Rinaldi Reviewed-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Test panel power savings sysfs

2026-07-15T13:15:39Z

[WHAT] Add KUnit coverage using a DRM-managed connector fixture. Tests cover show() mapping immediate-disable to 0 and reporting an active ABM level, and store() handling the disable mapping, the forbidden update, invalid text, and out-of-range input. show() writes through a page-backed buffer because sysfs_emit() requires one. Assisted-by: Copilot:Claude-Opus-4.8 Reviewed-by: Bhawanpreet Lakha Signed-off-by: Alex Hung Signed-off-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Test backlight device registration

2026-07-15T13:15:39Z

[WHAT] Add KUnit test to amdgpu_dm_register_backlight_device() and cover its bl_idx == -1 early return, which must leave the backlight device slot untouched. Assisted-by: Copilot:Claude-Opus-4.8 Reviewed-by: Bhawanpreet Lakha Signed-off-by: Alex Hung Signed-off-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Test backlight level readback path

2026-07-15T13:15:39Z

[WHAT] Add KUnit coverage for the backlight level read path. A faked link_service vtable returns canned PWM and AUX brightness values, letting the tests verify both the successful readback and the DC_ERROR/AUX-failure fallbacks to the cached brightness, plus the get_brightness() device-index wrapper. Assisted-by: Copilot:Claude-Opus-4.8 Reviewed-by: Bhawanpreet Lakha Signed-off-by: Alex Hung Signed-off-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Test backlight level programming path

2026-07-15T13:15:39Z

[WHAT] Add KUnit coverage for the backlight level write path in amdgpu_dm_backlight.c. Tests cover stream lookup hit/miss, the connector-off and no-stream early returns, and the AUX/PWM/idle-reallow programming branches. The DC programming calls stay safe by injecting a NULL power module and keeping idle optimizations a no-op via disable_idle_power_optimizations. Assisted-by: Copilot:Claude-Opus-4.8 Reviewed-by: Bhawanpreet Lakha Signed-off-by: Alex Hung Signed-off-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Fix backlight max_brightness to match exported range

2026-07-15T13:15:39Z

[Why] FWTS autobrightness fails on eDP panels because actual_brightness can read higher than the advertised max_brightness (e.g. 63576 vs 62451). The conversion helpers expose the firmware PWM range to userspace as [0..max]. But max_brightness is advertised as (max - min), which is smaller. So reading the level can return a value above max_brightness. This regressed in commit 4b61b8a39051 ("drm/amd/display: Add debugging message for brightness caps"), which changed max_brightness to (max - min) and undid commit 8dbd72cb7900 ("drm/amd/display: Export full brightness range to userspace"). [How] Advertise max_brightness as max, and scale the initial AC/DC brightness against max too. Update the KUnit expectations to match. Fixes: 4b61b8a39051 ("drm/amd/display: Add debugging message for brightness caps") Reviewed-by: Alex Hung Signed-off-by: Mario Limonciello Signed-off-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Enable CACP on Linux

2026-07-14T23:12:34Z

[Why] Enable OLED panels to save more power on the Linux platform by enabling CACP support on Linux. [How] Update abm_feature_support() to return ABM_CACP_SUPPORT for OLED panels. Enable ABM property for all eDP panels including OLED to support CACP via set_abm_level. Reviewed-by: Sun peng (Leo) Li Signed-off-by: Chenyu Chen Signed-off-by: George Zhang Signed-off-by: Alex Deucher

drm/amd/display: Extract backlight helpers for KUnit tests

2026-07-01T15:31:16Z

[WHAT] Extract shared backlight device index lookup and property setup into testable helpers. The duplicated bd-to-index scan in update_status/get_brightness is replaced by amdgpu_dm_backlight_get_device_index(), and the inline backlight_properties calculation is replaced by amdgpu_dm_backlight_fill_props(). Add KUnit coverage for both new helpers. Keep the runtime power_supply_is_system_supplied() call at the caller so the helpers remain pure and deterministic under test. Assisted-by: Copilot:GPT-5.5 Reviewed-by: Bhawanpreet Lakha Signed-off-by: Alex Hung Signed-off-by: George Zhang Signed-off-by: Alex Deucher